/* * socket.c -- socket library functions * * Copyright 1998 by Eric S. Raymond. * For license terms, see the file COPYING in this directory. */ #include "config.h" #include #include #include #include /* isspace() */ #ifdef HAVE_MEMORY_H #include #endif /* HAVE_MEMORY_H */ #include #ifndef HAVE_NET_SOCKET_H #include #else #include #endif #include #include #ifdef HAVE_ARPA_INET_H #include #endif #include #if defined(STDC_HEADERS) #include #endif #if defined(HAVE_UNISTD_H) #include #endif #if defined(HAVE_STDARG_H) #include #else #include #endif #include "socket.h" #include "fetchmail.h" #include "i18n.h" /* Defines to allow BeOS to play nice... */ #ifdef __BEOS__ static char peeked; #define fm_close(a) closesocket(a) #define fm_write(a,b,c) send(a,b,c,0) #define fm_peek(a,b,c) recv(a,b,c,0) #define fm_read(a,b,c) recv(a,b,c,0) #else #define fm_close(a) close(a) #define fm_write(a,b,c) write(a,b,c) #define fm_peek(a,b,c) recv(a,b,c, MSG_PEEK) #define fm_read(a,b,c) read(a,b,c) #endif /* We need to define h_errno only if it is not already */ #ifndef h_errno #ifdef HAVE_RES_SEARCH /* some versions of FreeBSD should declare this but don't */ extern int h_errno; #else /* pretend we have h_errno to avoid some #ifdef's later */ static int h_errno; #endif #endif /* ndef h_errno */ #if NET_SECURITY #include #endif /* NET_SECURITY */ #ifdef HAVE_SOCKETPAIR char *const *parse_plugin(const char *plugin, const char *host, const char *service) { const char **argvec; const char *c, *p; char *cp, *plugin_copy; unsigned int plugin_copy_len; unsigned int plugin_offset = 0, plugin_copy_offset = 0; unsigned int i, s = 2 * sizeof(char*), host_count = 0, service_count = 0; unsigned int plugin_len = strlen(plugin); unsigned int host_len = strlen(host); unsigned int service_len = strlen(service); for (c = p = plugin; *c; c++) { if (isspace(*c) && !isspace(*p)) s += sizeof(char*); if (*p == '%' && *c == 'h') host_count++; if (*p == '%' && *c == 'p') service_count++; p = c; } plugin_copy_len = plugin_len + host_len * host_count + service_len * service_count; plugin_copy = malloc(plugin_copy_len + 1); if (!plugin_copy) { report(stderr, GT_("fetchmail: malloc failed\n")); return NULL; } while (plugin_copy_offset < plugin_copy_len) { if ((plugin[plugin_offset] == '%') && (plugin[plugin_offset + 1] == 'h')) { strcpy(plugin_copy + plugin_copy_offset, host); plugin_offset += 2; plugin_copy_offset += host_len; } else if ((plugin[plugin_offset] == '%') && (plugin[plugin_offset + 1] == 'p')) { strcpy(plugin_copy + plugin_copy_offset, service); plugin_offset += 2; plugin_copy_offset += service_len; } else { plugin_copy[plugin_copy_offset] = plugin[plugin_offset]; plugin_offset++; plugin_copy_offset++; } } plugin_copy[plugin_copy_len] = 0; argvec = malloc(s); if (!argvec) { report(stderr, GT_("fetchmail: malloc failed\n")); return NULL; } memset(argvec, 0, s); for (c = p = plugin_copy, i = 0; *c; c++) { if ((!isspace(*c)) && (c == p ? 1 : isspace(*p))) { argvec[i] = c; i++; } p = c; } for (cp = plugin_copy; *cp; cp++) { if (isspace(*cp)) *cp = 0; } return (char *const*)argvec; } static int handle_plugin(const char *host, const char *service, const char *plugin) /* get a socket mediated through a given external command */ { int fds[2]; char *const *argvec; /* * The author of this code, Felix von Leitner , says: * he chose socketpair() instead of pipe() because socketpair creates * bidirectional sockets while allegedly some pipe() implementations don't. */ if (socketpair(AF_UNIX,SOCK_STREAM,0,fds)) { report(stderr, GT_("fetchmail: socketpair failed\n")); return -1; } switch (fork()) { case -1: /* error */ report(stderr, GT_("fetchmail: fork failed\n")); return -1; break; case 0: /* child */ /* fds[1] is the parent's end; close it for proper EOF ** detection */ (void) close(fds[1]); if ( (dup2(fds[0],0) == -1) || (dup2(fds[0],1) == -1) ) { report(stderr, GT_("dup2 failed\n")); exit(1); } /* fds[0] is now connected to 0 and 1; close it */ (void) close(fds[0]); if (outlevel >= O_VERBOSE) report(stderr, GT_("running %s (host %s service %s)\n"), plugin, host, service); argvec = parse_plugin(plugin,host,service); execvp(*argvec, argvec); report(stderr, GT_("execvp(%s) failed\n"), *argvec); exit(0); break; default: /* parent */ /* NOP */ break; } /* fds[0] is the child's end; close it for proper EOF detection */ (void) close(fds[0]); return fds[1]; } #endif /* HAVE_SOCKETPAIR */ #ifdef __UNUSED__ #include int SockCheckOpen(int fd) /* poll given socket; is it selectable? */ { fd_set r, w, e; int rt; struct timeval tv; for (;;) { FD_ZERO(&r); FD_ZERO(&w); FD_ZERO(&e); FD_SET(fd, &e); tv.tv_sec = 0; tv.tv_usec = 0; rt = select(fd+1, &r, &w, &e, &tv); if (rt == -1 && (errno != EAGAIN && errno != EINTR)) return 0; if (rt != -1) return 1; } } #endif /* __UNUSED__ */ int UnixOpen(const char *path) { int sock = -1; struct sockaddr_un ad; memset(&ad, 0, sizeof(ad)); ad.sun_family = AF_UNIX; strncpy(ad.sun_path, path, sizeof(ad.sun_path)-1); sock = socket( AF_UNIX, SOCK_STREAM, 0 ); if (sock < 0) { h_errno = 0; return -1; } if (connect(sock, (struct sockaddr *) &ad, sizeof(ad)) < 0) { int olderr = errno; fm_close(sock); /* don't use SockClose, no traffic yet */ h_errno = 0; errno = olderr; return -1; } return sock; } #if INET6_ENABLE int SockOpen(const char *host, const char *service, const char *options, const char *plugin) { struct addrinfo *ai, *ai0, req; int i; #if NET_SECURITY void *request = NULL; int requestlen; #endif /* NET_SECURITY */ #ifdef HAVE_SOCKETPAIR if (plugin) return handle_plugin(host,service,plugin); #endif /* HAVE_SOCKETPAIR */ memset(&req, 0, sizeof(struct addrinfo)); req.ai_socktype = SOCK_STREAM; if (getaddrinfo(host, service, &req, &ai0)) { report(stderr, GT_("fetchmail: getaddrinfo(%s.%s)\n"), host,service); return -1; } #if NET_SECURITY if (!options) requestlen = 0; else if (net_security_strtorequest((char *)options, &request, &requestlen)) goto ret; i = inner_connect(ai0, request, requestlen, NULL, NULL, "fetchmail", NULL); if (request) free(request); ret: #else /* NET_SECURITY */ #ifdef HAVE_INNER_CONNECT i = inner_connect(ai0, NULL, 0, NULL, NULL, "fetchmail", NULL); if (i >= 0) break; #else i = -1; for (ai = ai0; ai; ai = ai->ai_next) { i = socket(ai->ai_family, ai->ai_socktype, 0); if (i < 0) continue; if (connect(i, (struct sockaddr *) ai->ai_addr, ai->ai_addrlen) < 0) { fm_close(i); i = -1; continue; } break; } #endif #endif /* NET_SECURITY */ freeaddrinfo(ai0); return i; } #else /* INET6_ENABLE */ #ifndef HAVE_INET_ATON #ifndef INADDR_NONE #ifdef INADDR_BROADCAST #define INADDR_NONE INADDR_BROADCAST #else #define INADDR_NONE -1 #endif #endif #endif /* HAVE_INET_ATON */ int SockOpen(const char *host, int clientPort, const char *options, const char *plugin) { int sock = -1; /* pacify -Wall */ #ifndef HAVE_INET_ATON unsigned long inaddr; #endif /* HAVE_INET_ATON */ struct sockaddr_in ad, **pptr; struct hostent *hp; #ifdef HAVE_SOCKETPAIR if (plugin) { char buf[10]; #ifdef HAVE_SNPRINTF snprintf(buf, sizeof(buf), /* Yeah, paranoic. So what? :P */ #else sprintf(buf, #endif /* HAVE_SNPRINTF */ "%d",clientPort); return handle_plugin(host,buf,plugin); } #endif /* HAVE_SOCKETPAIR */ memset(&ad, 0, sizeof(ad)); ad.sin_family = AF_INET; /* we'll accept a quad address */ #ifndef HAVE_INET_ATON inaddr = inet_addr((char*)host); if (inaddr != INADDR_NONE) { memcpy(&ad.sin_addr, &inaddr, sizeof(inaddr)); #else if (inet_aton(host, &ad.sin_addr)) { #endif /* HAVE_INET_ATON */ ad.sin_port = htons(clientPort); sock = socket(AF_INET, SOCK_STREAM, 0); if (sock < 0) { h_errno = 0; return -1; } if (connect(sock, (struct sockaddr *) &ad, sizeof(ad)) < 0) { int olderr = errno; fm_close(sock); /* don't use SockClose, no traffic yet */ h_errno = 0; errno = olderr; return -1; } #ifndef HAVE_INET_ATON } #else } #endif /* HAVE_INET_ATON */ else { hp = gethostbyname((char*)host); if (hp == NULL) { errno = 0; return -1; } /* * Add a check to make sure the address has a valid IPv4 or IPv6 * length. This prevents buffer spamming by a broken DNS. */ if(hp->h_length != 4 && hp->h_length != 8) { h_errno = errno = 0; report(stderr, GT_("fetchmail: illegal address length received for host %s\n"),host); return -1; } /* * Try all addresses of a possibly multihomed host until we get * a successful connect or until we run out of addresses. */ pptr = (struct sockaddr_in **)hp->h_addr_list; for(; *pptr != NULL; pptr++) { sock = socket(AF_INET, SOCK_STREAM, 0); if (sock < 0) { h_errno = 0; return -1; } ad.sin_port = htons(clientPort); memcpy(&ad.sin_addr, *pptr, sizeof(struct in_addr)); if (connect(sock, (struct sockaddr *) &ad, sizeof(ad)) == 0) break; /* success */ fm_close(sock); /* don't use SockClose, no traffic yet */ memset(&ad, 0, sizeof(ad)); ad.sin_family = AF_INET; } if(*pptr == NULL) { int olderr = errno; fm_close(sock); /* don't use SockClose, no traffic yet */ h_errno = 0; errno = olderr; return -1; } } return(sock); } #endif /* INET6_ENABLE */ #if defined(HAVE_STDARG_H) int SockPrintf(int sock, const char* format, ...) { #else int SockPrintf(sock,format,va_alist) int sock; char *format; va_dcl { #endif va_list ap; char buf[8192]; #if defined(HAVE_STDARG_H) va_start(ap, format) ; #else va_start(ap); #endif #ifdef HAVE_VSNPRINTF vsnprintf(buf, sizeof(buf), format, ap); #else vsprintf(buf, format, ap); #endif va_end(ap); return SockWrite(sock, buf, strlen(buf)); } #ifdef SSL_ENABLE #include "openssl/ssl.h" #include "openssl/err.h" #include "openssl/pem.h" #include "openssl/x509.h" static SSL_CTX *_ctx = NULL; static SSL *_ssl_context[FD_SETSIZE]; SSL *SSLGetContext( int ); #endif /* SSL_ENABLE */ int SockWrite(int sock, char *buf, int len) { int n, wrlen = 0; #ifdef SSL_ENABLE SSL *ssl; #endif while (len) { #ifdef SSL_ENABLE if( NULL != ( ssl = SSLGetContext( sock ) ) ) n = SSL_write(ssl, buf, len); else n = fm_write(sock, buf, len); #else n = fm_write(sock, buf, len); #endif if (n <= 0) return -1; len -= n; wrlen += n; buf += n; } return wrlen; } int SockRead(int sock, char *buf, int len) { char *newline, *bp = buf; int n; #ifdef SSL_ENABLE SSL *ssl; #endif if (--len < 1) return(-1); #ifdef __BEOS__ if (peeked != 0){ (*bp) = peeked; bp++; len--; peeked = 0; } #endif do { /* * The reason for these gymnastics is that we want two things: * (1) to read \n-terminated lines, * (2) to return the true length of data read, even if the * data coming in has embedded NULS. */ #ifdef SSL_ENABLE if( NULL != ( ssl = SSLGetContext( sock ) ) ) { /* Hack alert! */ /* OK... SSL_peek works a little different from MSG_PEEK Problem is that SSL_peek can return 0 if there is no data currently available. If, on the other hand, we loose the socket, we also get a zero, but the SSL_read then SEGFAULTS! To deal with this, we'll check the error code any time we get a return of zero from SSL_peek. If we have an error, we bail. If we don't, we read one character in SSL_read and loop. This should continue to work even if they later change the behavior of SSL_peek to "fix" this problem... :-( */ if ((n = SSL_peek(ssl, bp, len)) < 0) { return(-1); } if( 0 == n ) { /* SSL_peek says no data... Does he mean no data or did the connection blow up? If we got an error then bail! */ if( 0 != ( n = ERR_get_error() ) ) { return -1; } /* We didn't get an error so read at least one character at this point and loop */ n = 1; /* Make sure newline start out NULL! * We don't have a string to pass through * the strchr at this point yet */ newline = NULL; } else if ((newline = memchr(bp, '\n', n)) != NULL) n = newline - bp + 1; if ((n = SSL_read(ssl, bp, n)) == -1) { return(-1); } /* Check for case where our single character turned out to * be a newline... (It wasn't going to get caught by * the strchr above if it came from the hack... ). */ if( NULL == newline && 1 == n && '\n' == *bp ) { /* Got our newline - this will break out of the loop now */ newline = bp; } } else { if ((n = fm_peek(sock, bp, len)) <= 0) return(-1); if ((newline = memchr(bp, '\n', n)) != NULL) n = newline - bp + 1; if ((n = fm_read(sock, bp, n)) == -1) return(-1); } #else #ifdef __BEOS__ if ((n = fm_read(sock, bp, 1)) <= 0) #else if ((n = fm_peek(sock, bp, len)) <= 0) #endif return (-1); if ((newline = memchr(bp, '\n', n)) != NULL) n = newline - bp + 1; #ifndef __BEOS__ if ((n = fm_read(sock, bp, n)) == -1) return(-1); #endif /* __BEOS__ */ #endif bp += n; len -= n; } while (!newline && len); *bp = '\0'; return bp - buf; } int SockPeek(int sock) /* peek at the next socket character without actually reading it */ { int n; char ch; #ifdef SSL_ENABLE SSL *ssl; #endif #ifdef SSL_ENABLE if( NULL != ( ssl = SSLGetContext( sock ) ) ) { n = SSL_peek(ssl, &ch, 1); if( 0 == n ) { /* This code really needs to implement a "hold back" * to simulate a functioning SSL_peek()... sigh... * Has to be coordinated with the read code above. * Next on the list todo... */ /* SSL_peek says no data... Does he mean no data or did the connection blow up? If we got an error then bail! */ if( 0 != ( n = ERR_get_error() ) ) { return -1; } /* Haven't seen this case actually occur, but... if the problem in SockRead can occur, this should be possible... Just not sure what to do here. This should be a safe "punt" the "peek" but don't "punt" the "session"... */ return 0; /* Give him a '\0' character */ } } else { n = fm_peek(sock, &ch, 1); } #else n = fm_peek(sock, &ch, 1); #endif /* SSL_ENABLE */ if (n == -1) return -1; #ifdef __BEOS__ peeked = ch; #endif return(ch); } #ifdef SSL_ENABLE static char *_ssl_server_cname = NULL; static int _check_fp; static char *_check_digest; static char *_server_label; static int _depth0ck; SSL *SSLGetContext( int sock ) { /* If SSLOpen has never initialized - just return NULL */ if( NULL == _ctx ) return NULL; if( sock < 0 || sock > FD_SETSIZE ) return NULL; return _ssl_context[sock]; } int SSL_verify_callback( int ok_return, X509_STORE_CTX *ctx, int strict ) { char buf[257]; X509 *x509_cert; int err, depth; unsigned char digest[EVP_MAX_MD_SIZE]; char text[EVP_MAX_MD_SIZE * 3 + 1], *tp, *te; EVP_MD *digest_tp; unsigned int dsz, i, esz; X509_NAME *subj, *issuer; x509_cert = X509_STORE_CTX_get_current_cert(ctx); err = X509_STORE_CTX_get_error(ctx); depth = X509_STORE_CTX_get_error_depth(ctx); subj = X509_get_subject_name(x509_cert); issuer = X509_get_issuer_name(x509_cert); if (depth == 0) { _depth0ck = 1; if (outlevel == O_VERBOSE) { if ((i = X509_NAME_get_text_by_NID(issuer, NID_organizationName, buf, sizeof(buf))) != -1) { report(stdout, GT_("Issuer Organization: %s\n"), buf); if (i >= sizeof(buf) - 1) report(stdout, GT_("Warning: Issuer Organization Name too long (possibly truncated).\n")); } else report(stdout, GT_("Unknown Organization\n")); if ((i = X509_NAME_get_text_by_NID(issuer, NID_commonName, buf, sizeof(buf))) != -1) { report(stdout, GT_("Issuer CommonName: %s\n"), buf); if (i >= sizeof(buf) - 1) report(stdout, GT_("Warning: Issuer CommonName too long (possibly truncated).\n")); } else report(stdout, GT_("Unknown Issuer CommonName\n")); } if ((i = X509_NAME_get_text_by_NID(subj, NID_commonName, buf, sizeof(buf))) != -1) { if (outlevel == O_VERBOSE) report(stdout, GT_("Server CommonName: %s\n"), buf); if (i >= sizeof(buf) - 1) { /* Possible truncation. In this case, this is a DNS name, so this * is really bad. We do not tolerate this even in the non-strict case. */ report(stderr, GT_("Bad certificate: Subject CommonName too long!\n")); return (0); } if (_ssl_server_cname != NULL) { char *p1 = buf; char *p2 = _ssl_server_cname; int n; if (*p1 == '*') { ++p1; n = strlen(p2) - strlen(p1); if (n >= 0) p2 += n; } if (0 != strcasecmp(p1, p2)) { report(stderr, GT_("Server CommonName mismatch: %s != %s\n"), buf, _ssl_server_cname ); if (ok_return && strict) return (0); } } else if (ok_return && strict) { report(stderr, GT_("Server name not set, could not verify certificate!\n")); return (0); } } else { if (outlevel == O_VERBOSE) report(stdout, GT_("Unknown Server CommonName\n")); if (ok_return && strict) { report(stderr, GT_("Server name not specified in certificate!\n")); return (0); } } /* Print the finger print. Note that on errors, we might print it more than once * normally; we kluge around that by using a global variable. */ if (_check_fp) { _check_fp = 0; digest_tp = EVP_md5(); if (digest_tp == NULL) { report(stderr, GT_("EVP_md5() failed!\n")); return (0); } if (!X509_digest(x509_cert, digest_tp, digest, &dsz)) { report(stderr, GT_("Out of memory!\n")); return (0); } tp = text; te = text + sizeof(text); for (i = 0; i < dsz; i++) { #ifdef HAVE_SNPRINTF esz = snprintf(tp, te - tp, i > 0 ? ":%02X" : "%02X", digest[i]); #else esz = sprintf(tp, i > 0 ? ":%02X" : "%02X", digest[i]); #endif if (esz >= te - tp) { report(stderr, GT_("Digest text buffer too small!\n")); return (0); } tp += esz; } report(stdout, GT_("%s key fingerprint: %s\n"), _server_label, text); if (_check_digest != NULL) { if (strcmp(text, _check_digest) == 0) report(stdout, GT_("%s fingerprints match.\n"), _server_label); else { report(stderr, GT_("%s fingerprints do not match!\n"), _server_label); return (0); } } } } if (err != X509_V_OK && (strict || outlevel == O_VERBOSE)) { report(strict ? stderr : stdout, GT_("Warning: server certificate verification: %s\n"), X509_verify_cert_error_string(err)); /* We gave the error code, but maybe we can add some more details for debugging */ switch (err) { case X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT: X509_NAME_oneline(issuer, buf, sizeof(buf)); buf[sizeof(buf) - 1] = '\0'; report(stdout, GT_("unknown issuer (first %d characters): %s\n"), sizeof(buf), buf); break; } } if (!strict) ok_return = 1; return (ok_return); } int SSL_nock_verify_callback( int ok_return, X509_STORE_CTX *ctx ) { return SSL_verify_callback(ok_return, ctx, 0); } int SSL_ck_verify_callback( int ok_return, X509_STORE_CTX *ctx ) { return SSL_verify_callback(ok_return, ctx, 1); } /* performs initial SSL handshake over the connected socket * uses SSL *ssl global variable, which is currently defined * in this file */ int SSLOpen(int sock, char *mycert, char *mykey, char *myproto, int certck, char *certpath, char *fingerprint, char *servercname, char *label) { SSL *ssl; SSL_load_error_strings(); SSLeay_add_ssl_algorithms(); if( sock < 0 || sock > FD_SETSIZE ) { report(stderr, GT_("File descriptor out of range for SSL") ); return( -1 ); } if( ! _ctx ) { /* Be picky and make sure the memory is cleared */ memset( _ssl_context, 0, sizeof( _ssl_context ) ); if(myproto) { if(!strcmp("ssl2",myproto)) { _ctx = SSL_CTX_new(SSLv2_client_method()); } else if(!strcmp("ssl3",myproto)) { _ctx = SSL_CTX_new(SSLv3_client_method()); } else if(!strcmp("tls1",myproto)) { _ctx = SSL_CTX_new(TLSv1_client_method()); } else { fprintf(stderr,GT_("Invalid SSL protocol '%s' specified, using default (SSLv23).\n"), myproto); myproto = NULL; } } if(!myproto) { _ctx = SSL_CTX_new(SSLv23_client_method()); } if(_ctx == NULL) { ERR_print_errors_fp(stderr); return(-1); } } if (certck) { SSL_CTX_set_verify(_ctx, SSL_VERIFY_PEER, SSL_ck_verify_callback); if (certpath) SSL_CTX_load_verify_locations(_ctx, NULL, certpath); } else { /* In this case, we do not fail if verification fails. However, * we provide the callback for output and possible fingerprint checks. */ SSL_CTX_set_verify(_ctx, SSL_VERIFY_PEER, SSL_nock_verify_callback); } _ssl_context[sock] = SSL_new(_ctx); if(_ssl_context[sock] == NULL) { ERR_print_errors_fp(stderr); return(-1); } /* This static is for the verify callback */ _ssl_server_cname = servercname; _server_label = label; _check_fp = 1; _check_digest = fingerprint; _depth0ck = 0; if( mycert || mykey ) { /* Ok... He has a certificate file defined, so lets declare it. If * he does NOT have a separate certificate and private key file then * assume that it's a combined key and certificate file. */ if( !mykey ) mykey = mycert; if( !mycert ) mycert = mykey; SSL_use_certificate_file(_ssl_context[sock], mycert, SSL_FILETYPE_PEM); SSL_use_RSAPrivateKey_file(_ssl_context[sock], mykey, SSL_FILETYPE_PEM); } SSL_set_fd(_ssl_context[sock], sock); if(SSL_connect(_ssl_context[sock]) == -1) { ERR_print_errors_fp(stderr); return(-1); } /* Paranoia: was the callback not called as we expected? */ if ((fingerprint != NULL || certck) && !_depth0ck) { report(stderr, GT_("Certificate/fingerprint verification was somehow skipped!\n")); if( NULL != ( ssl = SSLGetContext( sock ) ) ) { /* Clean up the SSL stack */ SSL_free( _ssl_context[sock] ); _ssl_context[sock] = NULL; } return(-1); } return(0); } #endif int SockClose(int sock) /* close a socket gracefully */ { #ifdef SSL_ENABLE SSL *ssl; if( NULL != ( ssl = SSLGetContext( sock ) ) ) { /* Clean up the SSL stack */ SSL_free( _ssl_context[sock] ); _ssl_context[sock] = NULL; } #endif #ifdef __UNUSED__ /* * This hangs in RedHat 6.2 after fetchmail runs for a while a * FIN_WAIT2 comes up in netstat and fetchmail never returns from * the recv system call. (Reported from jtnews * , Wed, 24 May 2000 21:26:02.) * * Half-close the connection first so the other end gets notified. * * This stops sends but allows receives (effectively, it sends a * TCP ). */ if (shutdown(sock, 1) == 0) { char ch; /* If there is any data still waiting in the queue, discard it. * Call recv() until either it returns 0 (meaning we received a FIN) * or any error occurs. This makes sure all data sent by the other * side is acknowledged at the TCP level. */ if (fm_peek(sock, &ch, 1) > 0) while (fm_read(sock, &ch, 1) > 0) continue; } #endif /* __UNUSED__ */ /* if there's an error closing at this point, not much we can do */ return(fm_close(sock)); /* this is guarded */ } #ifdef MAIN /* * Use the chargen service to test input buffering directly. * You may have to uncomment the `chargen' service description in your * inetd.conf (and then SIGHUP inetd) for this to work. */ main() { int sock = SockOpen("localhost", 19, NULL); char buf[80]; while (SockRead(sock, buf, sizeof(buf)-1)) SockWrite(1, buf, strlen(buf)); SockClose(sock); } #endif /* MAIN */ /* socket.c ends here */